Efficacy and safety of the pregnancy-IVI, an intravenous insulin protocol for pregnancy, following antenatal betamethasone in type 1 and type 2 diabetes

Aims: Hyperglycaemia following antenatal corticosteroids is common in women with diabetes in pregnancy, and validated algorithms to maintain pregnancy-specific glucose targets are lacking. The Pregnancy-IVI, an intravenous-insulin (IVI) algorithm, has been validated in gestational diabetes; however, its performance in pre-existing diabetes (Type 1 and Type 2 diabetes) is not known. We hypothesised that Pregnancy-IVI would be superior to a generic Adult-IVI protocol (prior standard of care) following betamethasone in women with pre-existing diabetes. Methods: A retrospective cohort study enrolled all women with pre-existing diabetes at a tertiary centre receiving betamethasone and treated with IVI according to one of two protocols: Adult-IVI (n = 73, 2014-2017) or Pregnancy-IVI (n = 62, 2017-2020). The primary outcome was on-IVI glycaemic time-in-range (capillary blood glucose (BGL) 3.8-7.0 mmol/L). Secondary outcomes included time with critical hyperglycaemia (BGL > 10 mmol/L); occurrence of maternal hypoglycaemia (BGL < 3.8 mmol/l) and incidence of neonatal hypoglycaemia (BGL ≤ 2.5 mmol/L). Analysis was stratified by diabetes type. Results: Overall, Pregnancy-IVI achieved a higher proportion of on-IVI time-in-range (70%, IQR 56-78%) compared to Adult-IVI (52%, IQR 41-69%, p < 0.0001). The duration of critical hyperglycaemia with Pregnancy-IVI was also reduced (2% [IQR 0-7] vs 8% [IQR 4-17], p < 0.0001), without an increase in hypoglycaemia. Glycaemic variability was significantly reduced with Pregnancy-IVI. No difference in the rate of neonatal hypoglycaemia was observed. The Pregnancy-IVI was most effective in women with Type 1 diabetes. Conclusion: The Pregnancy-IVI algorithm is safe and effective when used following betamethasone in type 1 diabetes in pregnancy. Further study of women with type 2 diabetes is required.